Load presets into the new C++ class.

lib/Slic3r.pm

@@ -163,6 +163,7 @@ sub thread_cleanup {
     *Slic3r::Surface::Collection::DESTROY   = sub {};
     *Slic3r::Print::SupportMaterial2::DESTROY = sub {};
     *Slic3r::TriangleMesh::DESTROY          = sub {};
+    *Slic3r::GUI::PresetBundle::DESTROY     = sub {};
     return undef;  # this prevents a "Scalars leaked" warning
 }
 

lib/Slic3r/GUI.pm

@@ -172,6 +172,7 @@ sub OnInit {
         }
     }
     $self->{mainframe}->config_wizard if $run_wizard;
+    eval { $self->{preset_bundle}->load_presets($datadir) };
     
 #    $self->check_version
 #        if $self->have_version_check